Testing new multi-channel analyser PHA capability for Cameca SX

[Gseward]

Gareth, could you do a PFE MCA scan in verbose setting and save the corresponding PeakSight PHA scan (they might be identical as PeakSight seems to update the PHA scans display even when collected by PFE)? Then we could really compare directly.

Cheers, Karsten

Karsten,

Here is a spreadsheet with numbers from PFE (using debug+verbose mode), I have pasted in the peaksight ASCII output that corresponds to the same scan.  Channel values correspond. Note: Cameca data has mV as x axis (0-5000mV), PFE has channel number. 

[Gseward]

Michel Outrequin offers these words of wisdom:

"The 256 intensities returned by the PHA routine are always from the minimum value (805 mV) to the maximum value (5637 mV)."

So I will change the MCA PHA limits in my code tonight...

presumably with the caveat that any Cameca with dynamic baseline hardware (newer SX100s and SX5) have values 0-5V !!!

[Probeman]

Michel Outrequin offers these words of wisdom:

"The 256 intensities returned by the PHA routine are always from the minimum value (805 mV) to the maximum value (5637 mV)."

So I will change the MCA PHA limits in my code tonight...

presumably with the caveat that any Cameca with dynamic baseline hardware (newer SX100s and SX5) have values 0-5V !!!

How does one determine if they have "dynamic baseline hardware (newer SX100s and SX5)"?  I mean from software...?  Maybe the easiest thing is to make this a user defined setting in the probewin.ini file?

[Gseward]

John,

I am confused: my assumption has been that the values reported in each channel were 'counts', and that the MCA was programmed to run until one channel hit 255 counts. Hence you needed to know the duration of testPHA in order to convert to cps. etc. etc.

I ask, because if you run testPHA with ~ no xrays (e.g. condenser at 4095 and the sample out of focus, or with 1kV beam etc) you get something that looks like this:



total count Integral = 9, Count Diff. = 5 in 19.906s, which seems to be about the maximum time the testPHA runs.   (values as reported by peaksight).

This seems to implies to me that some averaging and scaling is occurring in the MCA before the 'raw' values are reported.  Perhaps this is only the case in a situation where there is no meaningful count rate i.e. this test? and as such we can ignore it, but I worry that the 'raw' data might not be what it seems...

I wonder if this relates to the Y axis differences between traditional and MCA data??
   
ASCII output for image is attached - note values of either 0 or 255.

[Gseward]

Michel Outrequin offers these words of wisdom:

"The 256 intensities returned by the PHA routine are always from the minimum value (805 mV) to the maximum value (5637 mV)."

So I will change the MCA PHA limits in my code tonight...

presumably with the caveat that any Cameca with dynamic baseline hardware (newer SX100s and SX5) have values 0-5V !!!

How does one determine if they have "dynamic baseline hardware (newer SX100s and SX5)"?  I mean from software...?  Maybe the easiest thing is to make this a user defined setting in the probewin.ini file?

I would imagine that might be the easiest.

[Karsten Goemann]

Hi John,

"The 256 intensities returned by the PHA routine are always from the minimum value (805 mV) to the maximum value (5637 mV)."

These values don't make sense for my "old" SX100 (#846, 2003), which appears to have a range of 560-5560mV:
http://probesoftware.com/smf/index.php?topic=217.msg1038#msg1038

Aren't the above values just what is returned on your instrument?
http://probesoftware.com/smf/index.php?topic=217.msg1027#msg1027
http://probesoftware.com/smf/index.php?topic=217.msg1031#msg1031

If I do that test I get 1517 for baseline and 1125 for window:
http://probesoftware.com/smf/index.php?topic=217.msg1033#msg1033

This seems random, so these values might not be used for anything if the actual minimum and maximum values for the PHA scan are fixed as Michel says.

Looking at your own PeakSight PHA scans, they also seem to have a range of 0.56 to 5.56:
http://probesoftware.com/smf/index.php?topic=217.msg979#msg979

So I assume your instrument is "old" like mine. What happens on your instrument if you try to set a baseline below 560mV in PeakSight?

A agree that a probewin.ini flag for dynamic baseline minimum (and 0-5V PHA range) might be best.

[John Donovan]

I am confused: my assumption has been that the values reported in each channel were 'counts', and that the MCA was programmed to run until one channel hit 255 counts. Hence you needed to know the duration of testPHA in order to convert to cps. etc. etc.

That is what I was told by Michel... it returns when 255 count has been reached or after 20 seconds, whichever comes first.

[John Donovan]

"The 256 intensities returned by the PHA routine are always from the minimum value (805 mV) to the maximum value (5637 mV)."

These values don't make sense for my "old" SX100 (#846, 2003), which appears to have a range of 560-5560mV:
http://probesoftware.com/smf/index.php?topic=217.msg1038#msg1038

If I do that test I get 1517 for baseline and 1125 for window:
http://probesoftware.com/smf/index.php?topic=217.msg1033#msg1033

This seems random, so these values might not be used for anything if the actual minimum and maximum values for the PHA scan are fixed as Michel says.

Looking at your own PeakSight PHA scans, they also seem to have a range of 0.56 to 5.56:
http://probesoftware.com/smf/index.php?topic=217.msg979#msg979

So I assume your instrument is "old" like mine. What happens on your instrument if you try to set a baseline below 560mV in PeakSight?

A agree that a probewin.ini flag for dynamic baseline minimum (and 0-5V PHA range) might be best.

OK, so yes I agree this is confusing, I am just relying what Michel said.  But I have added new keywords in the [pha] section of the Probewin.ini file so you can set them to whatever you want...  post coming soon...

[John Donovan]

Ok, I've implemented the new MCA PHA keywords for Cameca instruments as follows:

[pha]
PHAMultiChannelMin=0.805   ; Cameca MCA PHA minimum x-axis voltage
PHAMultiChannelMax=5.637   ; Cameca MCA PHA maximum x-axis voltage

for the [pha] section of the Probewin.ini.

According to Michel, older Sx100 instruments use 0.804 and 5.637, but it may be different for newer instruments.

I've also indicated this with a version bump:

http://probesoftware.com/smf/index.php?topic=40.0

and a post to the "new" INI parameters thread started by Julien:

http://probesoftware.com/smf/index.php?topic=36.msg1067#msg1067

john

[Philipp Poeml]

This does not work for me. The values do not seem to apply to my machine. So, what is the best way to approach that? I do a traditional scan and then try to calibrate the MCA scan with the ini parameters?

It seems that the PfE traditoinal and PeakSight scans match pretty well.

So let's hope these ini values are not random... I mean different for every element...

For U Ma on a Qtz crystal for me the values are more 0.15 and 5.15. Strange enough: I plot the pha scan. I get a grid on the plot and lines. If I put my mouse on the grid line at 2.2 Volts, In the coordinate window it shows me 2.14 as the X coordinate. How can this be?

What means: ERROR in SX100GetPHADistributionMCASum : PHA MCA sum range parameters are equal and therefore represent a zero (invalid) range

[John Donovan]

The values do not seem to apply to my machine. So, what is the best way to approach that? I do a traditional scan and then try to calibrate the MCA scan with the ini parameters?

It seems that Cameca varied the x-axis voltage range with different instrument models. I think this is all we can do is check our own instrument and edit the Probewin.ini accordingly.

It seems that the PfE traditoinal and PeakSight scans match pretty well.

Good for you!  If they match well then you don't need to edit your Probewin.ini.   

For U Ma on a Qtz crystal for me the values are more 0.15 and 5.15. Strange enough: I plot the pha scan. I get a grid on the plot and lines. If I put my mouse on the grid line at 2.2 Volts, In the coordinate window it shows me 2.14 as the X coordinate. How can this be?

Where is this?  I need just a wee tiny bit more information unless we are playing "20 questions"!   

What means: ERROR in SX100GetPHADistributionMCASum : PHA MCA sum range parameters are equal and therefore represent a zero (invalid) range

I again need more details: how did you produce this error?  That is, under what conditions do you get the error?  I have not seen this error, it is only there for a code "sanity check".

[John Donovan]

I just got another reply from Michel. Now he says something different.

This morning, I ran a Test PHA on 4 different crystals (2TAPs and 1 PET on a L P spectro and 1 LPET on a high pressure spectrometer).  The corresponding text file is attached.  I was wrong, the Test PHA routine returns counts values between 0 and 5000mV as shown on the attached file.

I suspect that we are seeing that the older Sx100 instruments use 0.8 to 5.6 or so for the MCA PHA range, but newer Sx100s and SXFive instruments go from 0 to 5 volts?

[Philipp Poeml]

The values do not seem to apply to my machine. So, what is the best way to approach that? I do a traditional scan and then try to calibrate the MCA scan with the ini parameters?

It seems that Cameca varied the x-axis voltage range with different instrument models. I think this is all we can do is check our own instrument and edit the Probewin.ini accordingly.

This seams reasonable. I will try to do that.

It seems that the PfE traditoinal and PeakSight scans match pretty well.

Good for you!  If they match well then you don't need to edit your Probewin.ini.   

In fact I will have to edit. I said PfE traditoinal and PeakSight scans match pretty well. The PfE MCA scan does not fit by something around 0.2 and 0.3 Volts. But this seems variable.

For U Ma on a Qtz crystal for me the values are more 0.15 and 5.15. Strange enough: I plot the pha scan. I get a grid on the plot and lines. If I put my mouse on the grid line at 2.2 Volts, In the coordinate window it shows me 2.14 as the X coordinate. How can this be?

Where is this?  I need just a wee tiny bit more information unless we are playing "20 questions"!   

Sorry, I try to explain, but it seems I rarely succeed. Basically it is in any PHA plot, see this image. I tried to include the mouse coursor, but it did not show up in the screen shot: The tip is pointing exactly to the 2.2 Volts vertical line.

What means: ERROR in SX100GetPHADistributionMCASum : PHA MCA sum range parameters are equal and therefore represent a zero (invalid) range

I again need more details: how did you produce this error?  That is, under what conditions do you get the error?  I have not seen this error, it is only there for a code "sanity check".

Normally I was trying to do the PfE MCA scan with Count Time .1 and Intervals 40, the default values. I changed the Intervals to 60 and I got this error message. Still, the PHA scan seemed to display correctly.

[Probeman]

Sorry, I try to explain, but it seems I rarely succeed. Basically it is in any PHA plot, see this image. I tried to include the mouse coursor, but it did not show up in the screen shot: The tip is pointing exactly to the 2.2 Volts vertical line.

I see now what you mean. Yes, this is a "feature" of the graphics control I am using. It occasionally (though rarely) rounds the numbers on the graph tick mark labels so they aren't always as accurate as they could be.  So it is something that I can't directly control, but I will be implementing a new graphics control this year that will take care of this. 

In the meantime the mouse cursor X/Y display is the most accurate value.

What means: ERROR in SX100GetPHADistributionMCASum : PHA MCA sum range parameters are equal and therefore represent a zero (invalid) range

Normally I was trying to do the PfE MCA scan with Count Time .1 and Intervals 40, the default values. I changed the Intervals to 60 and I got this error message. Still, the PHA scan seemed to display correctly.

Ah, OK, I will check for this now! Thanks!

[Karsten Goemann]

John,

I've tested the new PHA MCA keywords in Probewin.ini a bit.

I can get a perfect match between PFE and PeakSight if I use PFE's verbose output of the 256 channels to the log window, see Excel plot screenshot attached. This is using 0.56V for the range minimum and 5.54V for the range maximum. The blue curve is not visible because it is completely covered by the green curve.

I'm using the same minimum and maximum values in Probewin.ini, but PFE's output of the same PHA scan (using the Export Data function in PHA | Display and Export Scans) seems scaled differently (red curve). This is using 0.1 for count time and 40 intervals.

How are you processing the data into 40 channels from 256? Would it be possible to just use the 256 raw channels and recalculate the x value based on the min-max settings? At the moment I can't set the intervals value for PHA acquisition to 256 without getting the error I've reported before.

Cheers,

Karsten